What hypothyroidism can cause
When the thyroid produces too little hormone, the body’s energy use slows. Possible symptoms include tiredness, cold intolerance, constipation, dry skin, muscle aches, menstrual changes, slower thinking, coarse or brittle hair and increased shedding. Many of these symptoms are common in people with normal thyroid function, which is why testing matters.
Why hypothyroidism may cause weight gain
An underactive thyroid can reduce energy expenditure and cause salt and water retention. The American Thyroid Association notes that thyroid-related weight gain is usually modest—often around 5 to 10 pounds depending on severity—and hypothyroidism by itself usually does not explain severe obesity. Once thyroid levels are normalized, persistent weight difficulty deserves a broader assessment.
Why thyroid disease can affect hair
Thyroid hormone helps regulate the hair-growth cycle. Too little or too much thyroid hormone can shift more follicles into a resting and shedding phase, causing diffuse thinning rather than one isolated patch. Hair recovery is slow because follicles need time to re-enter the growth phase, and iron deficiency, PCOS/PMOS, recent illness, rapid weight loss or a scalp disorder may also be present.
Fatigue: thyroid is one possibility, not the only one
Iron or vitamin B12 deficiency, poor sleep, sleep apnoea, depression, diabetes, chronic illness, calorie restriction and medicines may all cause fatigue. If TSH and free T4 are appropriate and symptoms persist, repeatedly increasing thyroid medicine can cause harm and may delay the real diagnosis.
How hypothyroidism is assessed
TSH is usually the first-line test for primary hypothyroidism. Free T4 helps clarify abnormal or discordant results and is essential when central thyroid disease is suspected. Thyroid antibodies may help identify autoimmune thyroid disease in selected situations but do not need to be repeated endlessly to adjust the dose.
Thyroid medicine: absorption and follow-up matter
Levothyroxine works best when taken consistently. Iron, calcium, antacids and some medicines can reduce absorption if taken too close together. TSH is generally reassessed after enough time has passed following a dose change, and pregnancy requires earlier and more frequent monitoring.
Thyroid nodules and goitre are a different question
Thyroid function tests measure how the gland works; they do not rule out a structural problem. A neck lump, enlargement, swallowing difficulty or suspicious nodule may require examination and ultrasound even when TSH is normal.
Why patients consult Dr. Fowad
Dr. Fowad’s practice connects thyroid assessment with weight, diabetes, PCOS/PMOS, hair concerns and metabolic health. Appointments are available in DHA Phase 6 and Garden Town, Lahore, and in Gujranwala. Referral is advised when surgery, pregnancy-specific management, cancer evaluation or another specialist service is needed.
Primary guidance
- American Thyroid Association: Hypothyroidism, accessed July 2026.
- American Thyroid Association: Thyroid and weight, 2024 patient resource.
- American Thyroid Association: Persistent symptoms and alternative causes, updated March 2024.
This information is general and cannot diagnose a thyroid condition. Neck swelling with breathing difficulty, severe palpitations, fainting or acute confusion requires urgent assessment.